Lewis, 18, was arrested Monday at 2 p.m. by the Los Angeles Police Southwest Division on suspicion of corporal injury on a spouse or cohabitant.
"USC takes all reports of domestic abuse seriously and is cooperating fully with the law enforcement investigation," school spokesman Tim Tessalone said in a statement. "While this student code of conduct issue is being investigated, the student has been suspended from all football-related activities. Student disciplinary records and student conduct proceedings are confidential at USC and protected by law."
Last year as a freshman, Lewis played in 11 games, mostly on special teams.